Basically, it complete replaces the textbox of whatever card is affected by it. Say, for example, if
Mecha'thun
was hit by this Battlecry, its text would read
"
Battlecry:
Replace the effect of a random minion in your opponent's hand with this Battlecry".
Meaning, it's original Battlecry wouldn't trigger when destroyed and, instead, spreads it out to one of your minions in it's place.

The effect can be reverted, though, by bouncing it back into your hand; the same way buffs and Silence dissapear when a minion is returned to it's owners hand.

5 mana 5/6 with an upside is pretty good, right? Paladin has the smallest, but also the weakest Secrets in general. Maybe you could transform them into something more useful.

Compare this to
Ethereal Peddler
, who only works in Burgle Rogue against non-Rogue classes, and requires some set-up. This only works in Secret Paladin, and requires some set-up. It also doesn't work with
Mysterious Challenger
because you can't play both in the same turn, unless you hit one of them with
Emperor Thaurissan
. MC will also use up all of your Secrets at once your opponent's next turn.

Interesting interaction: If by any means you have non-Paladin Secrets on the board, there's the possibility it will transform them into Paladin Secrets.

Someone can say it's unplayable and can compare it to
Shifter Zerus
. But the main idea of this card is flavour, and it have reference to name of this comp, cause it features the whole last year in HS.

this card was haunting me for months. a balance of this card has 2 aspects first everyone should have this card at their disposal. second, the keyword overpower is also a requirement for this card. You have to spend your turn playing this card. and it should transform into stats it gained meaning silencing it will not kill it